Data stored and transmitted electronically is vulnerable to theft Data storage devices, such as hard drives, flash drives, compact disks, memory chips and the like, whether portable or built into a computing device, are vulnerable to unauthorized remote access or the data being intercepted in transmission (i.e., “hacking”) if linked to a network. Data storage devices are also vulnerable to theft of the physical device.
One widely used means for preventing data theft is to store data in an encrypted format unreadable by unauthorized users. Such methods usually involve transforming the data with some sort of encryption algorithm. To read the encrypted data, a decryption key or algorithm must be used. Access to the decryption key or algorithm is typically limited to authorized users. Although encryption can protect data in many cases, one remaining vulnerability involves data stored by a data processing device such as a server or desktop computer in a cache. More specifically, if secure data is stored in a server or other bulk data storage devices, known as “backing storage,” access of the data is relatively slow compared to the data processing speed of the central processing unit (CPU) of modern computing devices. A solution to this is a cache, in which frequently retrieved data from backing storage devices is copied by the CPU and stored in main memory (i.e., in random access memory (RAM)) or in some other near-term storage such as flash memory. Alternatively, data from a server can be cached on local storage including hard drives or solid-state drives. Since cache copies are intended to be accessed quickly, they are often in unencrypted form even if the original copy was encrypted. However, data stored in the cache can be accessed like any other data on backing storage devices, and is thus likewise vulnerable to theft. Moreover, it is a copy of the most frequently accessed data from backing storage, which may be the most sensitive data stored on the backing storage device.